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/*
* Copyright (c) James Peach 2006
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "includes.h"
/* Commit data module.
*
* The purpose of this module is to flush data to disk at regular intervals,
* just like the NFS commit operation. There's two rationales for this. First,
* it minimises the data loss in case of a power outage without incurring
* the poor performance of synchronous I/O. Second, a steady flush rate
* can produce better throughput than suddenly dumping massive amounts of
* writes onto a disk.
*
* Tunables:
*
* commit: dthresh Amount of dirty data that can accumulate
* before we commit (sync) it.
*
* commit: debug Debug level at which to emit messages.
*
*/
#define MODULE "commit"
static int module_debug;
struct commit_info
{
SMB_OFF_T dbytes; /* Dirty (uncommitted) bytes */
SMB_OFF_T dthresh; /* Dirty data threshold */
};
static void commit_all(
struct vfs_handle_struct * handle,
files_struct * fsp)
{
struct commit_info *c;
if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
if (c->dbytes) {
DEBUG(module_debug,
("%s: flushing %lu dirty bytes\n",
MODULE, (unsigned long)c->dbytes));
fdatasync(fsp->fh->fd);
c->dbytes = 0;
}
}
}
static void commit(
struct vfs_handle_struct * handle,
files_struct * fsp,
ssize_t last_write)
{
struct commit_info *c;
if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
if (last_write > 0) {
c->dbytes += last_write;
}
if (c->dbytes > c->dthresh) {
DEBUG(module_debug,
("%s: flushing %lu dirty bytes\n",
MODULE, (unsigned long)c->dbytes));
fdatasync(fsp->fh->fd);
c->dbytes = 0;
}
}
}
static int commit_connect(
struct vfs_handle_struct * handle,
const char * service,
const char * user)
{
module_debug = lp_parm_int(SNUM(handle->conn), MODULE, "debug", 100);
return SMB_VFS_NEXT_CONNECT(handle, service, user);
}
static int commit_open(
vfs_handle_struct * handle,
const char * fname,
files_struct * fsp,
int flags,
mode_t mode)
{
SMB_OFF_T dthresh;
/* Don't bother with read-only files. */
if ((flags & O_ACCMODE) == O_RDONLY) {
return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
}
dthresh = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
MODULE, "dthresh", NULL));
if (dthresh > 0) {
struct commit_info * c;
c = VFS_ADD_FSP_EXTENSION(handle, fsp, struct commit_info);
if (c) {
c->dthresh = dthresh;
c->dbytes = 0;
}
}
return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
}
static ssize_t commit_write(
vfs_handle_struct * handle,
files_struct * fsp,
int fd,
void * data,
size_t count)
{
ssize_t ret;
ret = SMB_VFS_NEXT_WRITE(handle, fsp, fd, data, count);
commit(handle, fsp, ret);
return ret;
}
static ssize_t commit_pwrite(
vfs_handle_struct * handle,
files_struct * fsp,
int fd,
void * data,
size_t count,
SMB_OFF_T offset)
{
ssize_t ret;
ret = SMB_VFS_NEXT_PWRITE(handle, fsp, fd, data, count, offset);
commit(handle, fsp, ret);
return ret;
}
static ssize_t commit_close(
vfs_handle_struct * handle,
files_struct * fsp,
int fd)
{
commit_all(handle, fsp);
return SMB_VFS_NEXT_CLOSE(handle, fsp, fd);
}
static vfs_op_tuple commit_ops [] =
{
{SMB_VFS_OP(commit_open),
SMB_VFS_OP_OPEN, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(commit_close),
SMB_VFS_OP_CLOSE, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(commit_write),
SMB_VFS_OP_WRITE, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(commit_pwrite),
SMB_VFS_OP_PWRITE, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(commit_connect),
SMB_VFS_OP_CONNECT, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
};
NTSTATUS vfs_commit_init(void)
{
return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, MODULE, commit_ops);
}
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